pokeemerald

A complete decompilation of Pokémon Emerald for the Game Boy Advance — study, modify, and build upon the original game’s source code.

pokeemerald is the pret team’s complete decompilation of Pokémon Emerald for the Game Boy Advance. Every line of C and ARM assembly has been reverse-engineered from the original ROM. The project builds a byte-for-byte identical copy of the game, giving ROM hackers and researchers a fully readable, modifiable codebase.

Installation

Set up your build environment on Windows, macOS, or Linux and clone the repository.

Building

Compile pokeemerald.gba and verify it matches the original ROM checksum.

Project Structure

Navigate the source tree — src/, asm/, data/, include/, and the build toolchain.

Battle System

Explore the battle engine, AI, animations, and the Battle Frontier subsystem.

Scripting Guide

Write and modify event scripts, specials, and map scripts using the script engine.

Contributing

Learn the decompilation standards and how to submit clean, matching contributions.

Get up and running

1. Install dependencies

   Install build-essential, binutils-arm-none-eabi, git, and libpng-dev for your platform. See Installation for platform-specific instructions covering Windows (WSL1/msys2/Cygwin), macOS, and Linux.

2. Clone and install agbcc

   git clone https://github.com/pret/pokeemerald
   git clone https://github.com/pret/agbcc
   cd agbcc && ./build.sh && ./install.sh ../pokeemerald
   
3. Build the ROM

   cd pokeemerald
   make
   

   You will get pokeemerald.gba in the project root.

4. Verify the ROM

   make compare
   

   A passing result confirms your build is byte-for-byte identical to the original game: pokeemerald.gba: OK

What’s inside

Pokémon data

Base stats, moves, abilities, experience tables, and the GetMonData/SetMonData API.

World and maps

Map layouts, metatile behaviors, field effects, events, and the overworld engine.

Graphics and audio

GBA graphics pipeline, sprite/tileset rules, and the M4A audio engine.

Save system

Flash sector layout, SaveBlock structures, and save/load mechanics.

pokeemerald is a decompilation project — it is not affiliated with Nintendo or Game Freak. You need a legal copy of the original Pokémon Emerald ROM to verify your build. Distributing the compiled ROM is not permitted.